This invention relates to a single-handled mixing valve.
A known type of such a valve has two discs capable of sliding on each other and provided with orifices, one with inlet orifices and the other with an outlet orifice, the orifices being defined by curved surfaces calculated to ensure that a traversing or pivoting movement of one disc in relation to the other enables a constant ratio to be maintained between the areas of coincident orifice zones, and also enables the sum of the areas of the coincident zones to be kept constant. This first type suffers from the drawback of lack of precision, owing to the difficulty of constructing the orifices in a suitable manner.
In a second type there are two coaxial cylinders mounted one inside the other, one of the cylinders having the two inlet orifices and the other the outlet orifice. This second type, although attractive, presents major disadvantages. It is difficult to seal the orifices of the two cylinders from one another as required. If adequate sealing is achieved, the cylinders cannot be easily moved in relation to each other. Due to the lack of adequate clearance between them they tend to become jammed, particularly on expansion or scaling.